Advances in Nanotechnology and Nanoparticles in the 21st Century – An Overview Sunday A. Afolalu Department of Mechanical and Mechatronics Engineering, Afe Babalola University Ado Ekiti, Nigeria Department of Mechanical Engineering Science, University of Johannesburg, South Africa adeniran.afolalu@abuad.edu.ng Omolayo M. Ikumapayi, Olamilekan R. Oloyede Department of Mechanical and Mechatronics Engineering, Afe Babalola University, Ado Ekiti, Nigeria ikumapayi.omolayo@abuad.edu.ng, droloyede@abuad.edu.ng Temitayo S. Ogedengbe Department of Mechanical Engineering, Elizade University, Ilara-Mokin, Ondo State, Nigeria temitayo.ogedengbe@elizadeuniversity.edu.ng Adebayo T. Ogundipe Directorate of information Communication Technology, Afe Babalola University, Ado Ekiti, Nigeria bosundipe@abuad.edu.ng Abstract Nanotechnology is the branch of science and engineering that involves the study of particles at a dimension of as low as between 1 and 100 nanometers. These fine particles, referred to as nanoparticles, mostly are undetectable by human eyeand they find wide application in various fields ranging from drug delivery and chemotherapy, magnetism, optics, because of their remarkable traits and endearing properties they possess.This study therefore reviews the recent advancements in nanotechnology and nanoparticles. It dealt with different approaches in synthesis nanoparticles. The physicochemical properties and classifications of nanoparticleswere highlighted in the review. Keywords Nanotechnology, Nanoparticles, Nano, Materials, Century, Advance 1. Introduction Nanotechnology is among the most exciting and fast-moving scientific disciplines today. It is essentially a modern scientific discipline that is continually evolving as academic and commercial interest grows and as novel research is presented to the world of science(Pal et al., 2011). The simplest definition of nanotechnology is “technology on the nanoscale” (Nasrollahzadeh et al., 2019). Nevertheless, the definition of the nanoscale is indispensable for the definition of nanotechnology, which is a scale ranging between 1 to 100 nanometres (nm) (Ramsden, 2016). The prefix of the term “nanotechnology” is derived from the ancient Greek etymon “Nanos” and the Latin etymon “Nanus”, signifying dwarf or extremely small. By convention in the International System Units (SI), nano refers to 10 -9 power or one-billionth of a meter (Salman-Ali, 2020). In these terms, it refers to a nanometre, which is on the scale of the diameter of an atom (Wani, 2017). Nanotechnology involvestiny materials that are undetectable to neither the naked eye or a traditional light microscope ( Ramsden, 2016). "Nanometre" was a concept that was first proposed by Richard Adolf Zsigmondy. He proposed the term nanometre for explicitly characterizing and measuring the size of particles such as colloids with the use of a microscope (Ramsden, 2016). Richard Feynman (oftentimes regarded to as the Proceedings of the International Conference on Industrial Engineering and Operations Management Nsukka, Nigeria, 5 - 7 April, 2022 IEOM Society International 1200